A one-way street is a road where traffic is allowed to move in only one direction. This design helps to improve traffic flow and reduce the risk of accidents by preventing vehicles from coming head-to-head. One-way streets are often found in urban areas where space is limited and can help to manage congestion. Drivers must pay attention to signs indicating that a street is one-way, as entering from the wrong direction can lead to dangerous situations. Cities like New York and San Francisco utilize one-way streets to enhance navigation and safety for both vehicles and pedestrians.